Apparatus for casting electrotypes



Feb. 26, 1957 H. L. BISHOP APPARATUS FOR CASTING ELECTROTYPES 6Sheets-Sheet 2 Filed May 2, 1952 IN V EN TOR.

Feb. 26, H. L. BISHOP 2a782474 APPARATUS FOR CASTING ELECTROTYPES FiledMay 2, 1952 e Sheefs-Sheet s ZN V EN TOR.

Feb. 26, 1957 H. L., BISHOP APPARATUS FOR CASTING ELECTROTYPES 6 Sheets4 Filed I Ma 2 1952 Om N6 INVENTOR, Z fl fl Feb. 26, 1957 H. BISHOPAPPARATUS FOR CASTING ELECTROTYPES 6 She ets-Sheet 5 Filed May 2, 1952IN V EN TOR.

Feb. 26, 1957 H. BISHOP APPARATUS FOR CASTING ELECTROTYPES 6Sheets-Sheet 6 Filed May 2, 1952 mom United States Patent APPARATUS FORCASTING ELECTROTYPES Application May 2, 1952, Serial No. 285,818

8 Claims. (Cl. 22-58) This invention relates to an apparatus formanufacturing electrotype plates from a shell having backing metalapplied to the rear thereof.

This application is a continuation-in-part of my copending applicationSerial No. 758,515, filed July 2, 1947, for Process of ProducingElectrotypes, now abandoned.

In the printing industry electrotype plates are used for printingvarious types of publications, advertising material, posters, et cetera.A great number of electrotype plates are required for each edition ofmagazines having circulations in the millions, and especially magazineshaving a number of illustrations. Due to the fact that some of thesemagazines are published weekly, the problem of producing the electrotypeplates promptly and efiiciently is what might be referred to as one ofthe bottle-necks in the industry.

In the first place, it is necessary to make a mat for use from copperthat may have the face electroplated with some other metal that isharder and somewhat more wear resistant, as for example, nickel orchrome. The rear side of the shell is then tinned, so as to cause thebacking metal, usually consisting of lead, antimony and tin, to adherethereto. In other words, the tin coating forms a bond.

A number of problems are presented in casting the backing metal upon therear side of the shell. Asis well known to those skilled in the art,lead has a very high specific gravity. It is very heavy. Copper, theprincipal metal used in the shell, is much lighter. By placing the shellin the bottom of the mold cavity and then applying backing metal to therear thereof, the shell wants to float, unless some precautionarymeasure is taken to prevent the shell from rising upwardly in thebacking metal. Various modes have been used in attempting to prevent theshell from lifting up from the bottom of the mold cavity. In the past,it has been rather common practice to pour the backing metal on the rearof the shell by means of a ladle. This takes time and requires aconsiderable amount of skill. Furthermore, if the shell is not perfectlyflat and in intimate contact with the bottom of the mold cavity, theheavy molten metal will flow under the shell, destroying at least a partof the printing area.

When casting electrotype plates by the methods formerly used, theelectrotype warps and is drawn out of shape when solidification takesplace. By pouring molten metal on the rear of the shell in a cold mold,tremendous stresses are set up in the cast metal, in that thesolidification is not uniform. The portions of the molten metal comingin contact with the cold walls of the mold solidify almost instantly,whereas other portions of the molten metal remain molten for a longerperiod of time. This uneven solidification of the metal results inwarping of the electrotype plate. Furthermore, stresses are set upbetween the cold shell and the molten metal, in that the shell absorbsheat, thereby expanding, while the molten metal coming in contact withthe rear cold shell contracts,

in electrodepositing the shell. This shell is usually made" 2,782,474Patented Feb. 26, 1957 setting up opposing forces tending to warp thefinished product and also tending to cause a rupture between the shelland the backing metal. Furthermore, there are no forces counteractingthetendency to warp, for the reason that the shell and the backing metallie loosely in the bottom of the mold cavity. In view of this situation,it has been the practice in the past to first submit the plate to apressure so as to straighten the shell, forcing the printing surfaceinto a common plane. This is followed by shaving the rear of theelectrotype plate, so as to reduce' it to the desired thickness.

The electrotype plate may then be solidified by a device disclosed in myPatent No. 2,580,723, issued January 1, 1952, for Preliminary FinishingMachine. Treatment may be placed in the electrotype plate by the use ofmake-readies made according to the processes disclosed in my Patent No.2,088,398, issued July 27, 1937, for Printing Process and my Patent No.2,256,921, issued September 23, 1941, for Make-ready. Due to the factthat the electrotype plate may be solidified very rapidly and treatedefficiently and speedily, it is desirable to improve upon the methods ofcasting the electrotype plates, so as to produce the electrotype platesmore rapidly in readiness for the subsequent operations and at the sametime produce a better product.

An object of this invention is to provide a machine for automaticallysubmerging the molds in molten metal while the shell is physically heldin intimate contact with the bottom of the mold cavity, then a device isused for compressing the cast metal during the solidification thereof,so as to insure the face of the electrotype plate coming out of the moldin a flat condition to eliminate the step of flattening the plate, sothat as the finished electrotype plate comes out of the casting machine,it is ready for solidification.

Other objects and advantages reside in the construction of parts and thecombination therof, as will become more apparent from the followingdescription.

In the drawings, Figure 1 is a top plan view of the machine for castingthe electrotype plates and carrying out the process.

Figure 2 is a side elevational view of the machine shown in Figure 1.

Figure 3 is a top plan view of a mold provided with means for retainingthe shell in the bottom thereof.

Figure 4 is a cross sectional view taken substantially on line 4-4 ofFigure 3.

Figure 5 is a top plan view of a mold cavity shown without the devicefor exertingpressure upon the rear of the shell. p

Figure 6 is an end elevational view of the mold showing a portion of theconveyor in section.

Figure 7 is an enlarged fragmentary and detail view of the mechanism forcausing the mold to travel downwardly into the vat of molten metal.

Figure 8 is a sectional view taken substantially on the line 88 ofFigure 7.

Figure 9 is an enlarged, fragmentary, side elevational view of themechanism for holding the mold down in the molten metal vat.

Figure 10 is a fragmentary, cross sectional view taken substantially onthe line 1010 of Figure 9.

Figure 11 is an enlarged, fragmentary view of a portion of the side ofthe machine showing the mold in a tilted position as it advances out ofthe vat.

Figure 12 is a fragmentary, cross sectional view taken substantially onthe line 1212 of Figure 11.

Figure 13 is an enlarged, top plan view of a mold having the castbacking metal therein and having mounted thereon a metal compressingdevice.

spasms Figure 14 is a cross sectional view of the mold takensubstantially on the line 1414 of Figure 13.

Figures 3-5 have been drawn on a larger scale than Figures 1 and 2 andon a smaller scale than Figures 7-14 inclusive.

Referring to the drawings, the reference character 20 indicates aplurality of supports located on each side of the machine. Thesesupports 20 on each side cooperate to support a laterally disposed framemember 22, shown in Figure 8, there being one frame member on each side.End posts 24 are mounted adjacent the ends. The sides of the machine areenclosed by a suitable apron 26. The frame structure is adequatelybraced in any suitable manner.

A pair of sprocket wheels 28 is journaled in bearings 30 adjustablymounted upon the frame member 22. The bearings 30 are mounted foradjustment and held in adjusted position by screws 32 threadedlyengaging suitable supports 34. The opposite end of the frame supports apair of sprocket wheels 40 mounted upon a drive shaft 42 journaled insuitable bearings 44. The drive shaft 42 is driven from an electricmotor 46 through a suitable gear box, not shown.

A pair of conveyors consisting of chains 48 and 50 extend throughout thelength of the machine and pass over the sprocket wheels 28 and 40. Bythis arrangement it can readily beseen that when the motor 46 isenergized, the chains 48 and 50 will be driven by the sprocket wheels40. These chains are tightened or tensioned by the adjusting screws 32.The two chains 48 and 50 have the same number of links, so that the twochains will rotate in unison. The rate of travel ofthe chains is quiteslow, in that it takes several minutes for a chain to make a completerevolution. Furthermore, the rate of travel of the conveyors may bechanged by changing the speed of the motor or by changing the gear ratioof the gear box.

A plurality of molds 60 are mounted on crank arms 62, there being fourcrank arms for supporting each mold, two crank arms on each side. Thesecrank arms are provided with pins 64 extending at right angles to thelength of the machine and are pivotally mounted in the sides of the mold60. In the end of the crank arms opposite the pins 64 are mounted pins66 pivotally journaled in suitable sockets in lugs 67 attached to theconveyor chains 48 and 50. The pins 66 also extend at right angles tothe longitudinal length of the machine, but in the opposite directionfrom the pins 64. There is considerable clearance between the pins 64and 66 and the apertures, recesses or sockets therefor in the molds andthe lugs respectively to allow for free movement of the mold into thevarious levels and inclinations without binding.

As may best be seen by referring to Figure 4, one end of the mold isprovided with a transverse recess or aperture 70. The opposite end ofthe mold is-provided with an inclined aperture or recess 72. As themolds are advanced into a horizontal position shown to the extreme leftof Figures 1 and 2, the operator places a shell 80 in the bottom of themold. This shell 80, as seen in Figure 4, consists of a sheet of copperthat has been electrodeposited and has an irregular surface forming theprinting surface. This printing surface may be protected by suitablehard metal, such as nickel or chrome, electroplated on the printing sideof the shell. The printing surface is placed in the bottom of the moldcavity. The rear of the copper shell has been tinned, the tinned surfaceforming a bond between the shell and the backing metal of the finishedelectrotype plate, as is wellknown to those skilled in the art.

Due to the fact that the backing metal consists of lead, antimony andtin, the lead predominating, it can readily be seen that the shell,which has a much lower specific gravity, wil tend to float or raiseupwardly from the bottom of the mold cavity when the mold is submergedin molten backing metal. That being the case, the submerging of the moldwith the shell in the bottom thereof presents a problem, in that theshell tends to rise upwardly, so that backing metal will flow under theshell. Furthermore, in the event there are any kinks or wrinkles orbulges in the margins of the shell, the molten metal will flow underthese raised portions.

As may best be seen by referring to Figure 4, a plurality of springs 82,arranged in close proximity to each other throughout the entire area ofthe shell, are compressed against the rear of the shell by a cappingmember 84 provided with a marginal flange 86 along one side thereof.This flange 86 is provided with a pair of projections 88 extending intothe aperture 70 in the end of the mold. A lever 90 is pivotally attachedto member 84 on the end opposite the projections 88. The lever 90 isprovided with a prong or projection 92 hooked into the aperture 72.Member 84 together with the springs 82are placed in position on the moldimmediately after the shell is laid in position. The springs 82,engaging the shell in a number of areas throughout the rear of theshell, exert a pressure on the rear of the shell, flattening the shellout, removing wrinkles and bulges therein, and firmly hold the shell inthe bottom of the mold. The strength of the springs is such that whenengaging the rear surface of the shell the force exerted upon each areaof the shell is greater than the weight of a column of metal extendingfrom the shell to the top of the vat which will be described more fullyhereinafter. By this arrangement the force exerted by the springspressing the shell against the bottom of the mold is sufficient to morethan offset the buoyancy of the shell submerged in a vat of moltenmetal.

Member 84 is open along the margins 94 and 96, so that there is a gap 98between member 84 and the top margin 100 on the one side of the mold anda similar gap between the top margin 102 on the opposite side of themold, which top margins are best seen in Figures 5 and 6. The distancefrom the top of the margin 102, which is the trailing margin of themold, to the bottom of the mold cavity is held within predeterminedtolerances for reasons that will appear more fully later.

As can best be seen by Figures 3 and 4, the top margins 104 and 106 ofthe ends of the mold are exposed when member 84, together with thesprings thereon, is locked in position. The mold, as it advances, isguided upon a pair of rails 108, so as to be maintained in a horizontalposition. The rails 108 terminate near the edge of a vat or tank 110. Arail or guide 112, which is arranged at an angle, is used to support theleading edge of the mold 60, as shown in Figure 7.

A cam 114 actuated by a sprocket wheel 116 driven by the conveyor chain48 is mounted in a position such that the cam 114 rides on the margin106 and a like cam on the opposite end of the shaft 118 contacts themargin 104, so as to tip the mold downwardly into the molten metal foundin the vat 110. The cam 114 rotates through one revolution or multiplethereof in the distance equal to the spacing of the molds on theconveyor, so that the cam is properly synchronized with the travel ofthe molds. The mold advances under the friction wheels 120 and 122 thathold the mold cavity on rails 124 horizontally disposed in the bottom ofthe vat 110. The top of the mold is below the level of the liquid in thevat, so that the shell mounted in the bottom thereof is submerged in themolten metal.

The wheels 120 and 122 are journaled upon stub shafts 126 secured intolateral frame members 128 secured to the frame member 22. An arcuatemember 130 is used in supporting the shaft 126 in a horizontal position.There is a considerable upward pressure on the wheels 120 and 122, inthat the material used in producing the mold and the parts in the moldare much lighter than the molten metal. That being the case, there is atendency for the mold and the contents thereof to rise upwardly andfloat on the molten metal.

A rail or guide 140 pivotally attached to the horizontal rail 142extending beyond the vat is used in guiding the mold out from the moltenmetal. This rail 140 is adjustably mounted, so that the angle ofinclination thereof may be adjusted. This adjustment is accomplished bymeans of a shaft 144 positioned in the slot 146 in member 140. The shaft144 is fixedly mounted in a gear 148 meshing with a gear 150 controlledby a suitable hand wheel 152, so that by rotating the hand wheel 152,the gear 150 actuates the gear 148 to raise or lower the lower end ofthe rail 140. The shaft 144 extends through the opposite side of thevat, so as to actuate the rails on both sides in unison. The lower endof the rail 140 is attached by a suitable pivot 160 to a rail segment162 in the bottom of the vat, so that as the angle of inclination of therail or member 140 is raised, the one end of the rail 162 is adjustedupwardly or downwardly, so as to cause the leading edge of the moldcavity as it advances towards the rail 140 to actually engage this rail.

As the mold is advanced by the chains 48 and 50 advancing, the mold isgradually withdrawn from the vat of molten metal. The inclination of therail 140 is such that as the mold is guided out of the vat, the surplusmolten metal will be spilled out over the top margin or trailing edge100 of the mold. The inclination of the rail 140 is so adjusted that theproper amount of molten metal will remain in the mold to provide theproper thickness of the backing metal when the mold is advanced intohorizontal position.

In the event the backing metal is too thick, the angle of inclination ofthe rail 140 is increased to empty more metal out of the mold whenwithdrawn from the vat. On the other hand, if the backing metal is toothin, the angle of inclination of the rail 140 is decreased so as toleave more metal in the mold. All of the molds are sub stantiallyidentical, so that the same quantity of metal remains in each successivemold passing through the vat with the same setting of the guide rails140.

The molten metal in the vat 110 is maintained in a molten state by aplurality of gas fired burners 170 automatically controlled by theautomatic controls 172. The molten metal is maintained at a temperatureslightly above the melting point of the metal, so that shortly after themold is withdrawn from the vat, the metal begins to solidify. In orderto prevent too rapid a solidification of the metal coming in contactwith the walls of the mold, the molds are also heated by the burners170, in that the burners supply heat in the compartment for the returnof the molds, so that the molds are maintained hot and raised to thedesired temperature while returning, so that the temperature of the moldupon being submerged in the vat is substantially equal to thetemperature of the molten metal. A cover is mounted between the upperand lower track for the chains, so as to reduce the heat losses and soas to supply heat to the returning molds.

As soon as the mold advances into the horizontal position immediatelypast the vat, the springs 82 and the capping member 84 are removed. Thismay be accomplished by the use of a bar 180 shown in Figures 13 and 14.One end of the bar 180 is provided with a deflected portion 182projecting into an aperture in the capping member 84. By pressingdownwardly on the outer end of thebar 180, the lever or latch member 90may be rotated in a counter-clockwise direction, so as to permit theprong or projection 92 to clear the aperture 72. The capping member 84and the springs 82 may then be raised and the lower ends of the springs82 lifted out of the molten metal. However, due to the fact that therear of the shell is completely covered with molten metal, the shellremains in the bottom of the mold cavity. The mold, together with theshell and the backing metal,

moves slowly towards the right, as viewed in Figures 1 and 2. The metalsoon begins to solidify.

At the proper time ametallic shim 200 is laid on top of the freshly castbacking metal 202, as best seen in Figure 14. The capping member 84 andthe springs 82 are then again inserted into position, as shown in Figure14, by projecting the projection 88 into the aperture 70 and latchingthe projection 92 carried on the lever into the aperture 72. The springsare now in greater compressicn than they were when holding down theshell, in that the springs have been compressed an additional distanceequal to the distance from the top of the shell to the top of the shim.

The springs 82 cooperate with the shim 200 to exert a pressure over theentire rear area of the backing metal, so as to firmly press the shellinto contact with the bottom of the mold cavity. By this arrangement,warping of the shell and the backing metal is deterred and practic'allyeliminated. Furthermore, by'exerting the pressure upon the rear of theshim overlying the metal that is being solidified, the pressure exertedon this metal tends to eliminate or reduce blow holes and voids in thebacking metal and thereby tends to reduce the undesirable effect causedby what is generally referred to in the trade as soft spots in thefinished electrotype plate.

When the mold approaches the sprocket wheels 40, the capping member '84,the springs 82, and the shim 200 are removed. The period of time that ittakes for the mold to travel from the molten metal to the sprocket wheel40 is sufiicient to permit solidification of the cast metal, so that asthe mold is carried over the end of the machine, the mold is invertedand the cast electrotype plate drops out of the mold and may be carriedaway on a suitable conveyor not shown.

The mold has not cooled so very much, in that it takes only a fewdegrees temperature drop to cause the metal to solidify, and that beingthe case, in returning in the compartment located below the top of thelower tier of the conveyor, the mold absorbs sufficient heat from thegas burners, so that when it returns -to the horizontal position on theleft-hand end of the machine, asviewed in Figures 1 and 2, thetemperature of the mold is substantially the same as the temperature ofthe molten metal. The distance from the left end of the machine to thevat for the molten metal is quite short as compared to the distance fromthe vat to the sprocket wheel 40 on the opposite end of the machine.

Mode of operation While the mold is advancing into the horizontalposition on the left-hand end of the machine, as viewed in Figures 1 and2, a shell is placed in the bottom of the mold. This shell is preferablycentered with respect to the mold. The springs 82 are then placed on topof the shell and the capping member 84 locked in position, the springsexertinga uniform pressure in numerous uniformly spaced areas throughoutthe entire rear of the shell.

Due to the fact that the mold is hot as it advances into the horizontalposition to the left of the machine, as viewed in Figures 1 and 2, theshell absorbs heat from the mold. Copper being a good conductor causesthe shell to heat rapidly, so that by the time that the mold and theshell reach the vat, the shell has a temperature substantially equal tothe temperature of the molten metal.

The mold dips into the vat so that the mold cavity is completelysubmerged in the molten metal. The level of the metal in the vat ispreferably maintained auto matically at a constant height. The mold,advancing into the molten metal at an angle, tends to expel all air asthe mold gradually advances into the vat, thereby reducing thepossibility of blow holes. Furthermore, the mold travels through themolten metal for a considerable period of time, which permits any gasbubbles or air bubbles to rise to the surface while the mold istraveling through the molten metal.

The mold being withdrawn from the molten metal is withdrawn at apredetermined angle, so as to maintain a predetermined amount of moltenmetal in the mold cavity. This molten metal is, so to speak, located inone corner of the mold while the mold is being withdrawn from the moltenmetal. As the mold advances into the horizontal position, the moltenmetal spreads uniformly throughout the area of the mold, so as to causethe molten metal to have a uniform depth.

The springs 82 and the capping member 84 have been held in positionduring the entire travel of the mold through the vat of molten metal.Immediately upon the mold being removed from the vat, the capping member84 and the springs 82 are removed before the backing metal begins tosolidify. As soon as the backing metal has cooled sufliciently so as tosupport the shim 200, the shim is placed on top of the backing metal andthe capping member 84 together with the springs 82 are inserted on therear of the shim to exert a force on top of the shim, clamping the shellflat against the bottom of the mold cavity. The tension of the springsholding the shim in position is far greater than the tension used whenengaging the shell in the bottom of the mold during submersion of themold. The compressive force of the springs has been so chosen that theproper force is exerted on the rear of the electrotype plate.

The springs 82 and the capping member 84 remain in position until themold reaches the extreme right of the machine, as viewed in Figures 1and 2, when the capping member 84 and the springs 82 together with theshim 200 are removed. As the mold travels around the end of the path ofthe conveyors or chains 48 and 50, the electrotype plate automaticallydrops out of the mold upon a suitable ledge or conveyor in readiness forthe subsequent operations.

The electrotype plate produced by this method need not first becompressed so as to flatten the shell, but it may be treated in thesolidifying machine disclosed in my Patent No. 2,580,723, therebyeliminating the step of flattening the shell or removing theirregularities out of the electrotype plate after it is removed from themold.

Instead of one shell being located in the bottom of the mold cavity,several small shells may be inserted in the bottom of the mold cavityside by side, so as to provide a backing metal for a plurality ofelectrotype plates in the same mold cavity. The size of the mold cavityis a matter of choice, depending upon the requirements of the particularmachine.

The temperature of the molten metal may be adjusted, so that thetemperature of the molten metal is slightly above the melting pointthereof. In the event the ingredients of the molten metal are changed,resulting in a change in the melting point, the controls for the heatingelements used in heating the vat are adjusted automatically. Instead ofutilizing gas burners, electric burners could be used, the type ofburners or heating elements being determined by the available source ofheat and the cost thereof.

Each mold together with the electrotype plate thereon is heavy. Thatbeing the case, as the molds travel over the rails 108 and 109, there isconsiderable friction and the parts wear rather rapidly. Instead ofusing solid rails 108 and 109, the molds preferably travel over rollersarranged in tandem, so that the molds roll across the rollers. Thisreduces wear on the parts, thereby retaining the dimensions of the moldssubstantially uniform throughout a longer period of time. When thebottoms of the molds wear, it is then necessary to adjust the angle ofinclination of rails 140, so as to tilt the molds to the proper angle topour out the surplus metal.

The height of the end flanges or top margins 104 and 106 of the molds ispreferably sufiiciently high, so as to be located above the level of themolten metal in the vat when the molds are traveling through the vat.The height may be increased, if necessary, to obtain sufficient headpressure of the column of molten metal above each square inch of shell.

The molds travel rather slowly, so that ample time is provided forsolidification of the metal from the time that the molds are withdrawnfrom the molten metal until the molds are tipped to dump the electrotypeplates. If it is found desirable to increase the output of the machine,the conveyor may be lengthened and the rate of travel of the molds maybe increased so that suflicient time elapses between the time that themold is withdrawn fro-m the molten metal until the electrotype plate isdumped to permit solidification of the backing metal. By doubling thespeed at which the molds travel, the length of the conveyor beyond thevat to the position where the electrotype plate is dumped should bedoubled in order to allow the same time for the solidification of themolten metal.

Although the preferred embodiment of the device has been described, itwill be understood that within the purview of this invention variouschanges may be made in the form, details, proportion and arrangement ofparts, the combination thereof and mode of operation, which generallystated consist in a device capable of carrying out the objects setforth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. A machine for use in the manufacture of electrotype plates, thecombination including a continuous length conveyor advancing in onedirection in a horizontal plane and in the opposite direction in ahorizontal plane on a lower level, a plurality of molds, means formounting the molds on the conveyor, said means including a plurality ofcrank arms for supporting each mold, each of said crank arms having oneend pivotally mounted on the conveyor and the opposite end pivotallyattached to the mold, guide rails for supporting the molds in ahorizontal position, a vat for molten metal located between the upperand lower levels of the conveyor, means for tilting the molds downwardlyinto the molten metal and guiding the molds through the vat of moltenmetal, and means for raising the molds at an inclined angle from themolten metal, said last mentioned means being adjustable so as to alterthe angle of inclination of the mold so that as the mold is removed fromthe molten metal the quantity of metal remaining in the mold equals thevolume of the backing metal desired for the electrotype plate when cast,the conveyor advancing the molds with the molten metal thereinhorizontally while the metal is being cooled so as to cause the metal tosolidify, the conveyor upon advancing from the horizontal position onone level to the horizontal position in the other level tilting themolds so as to permit the cast electrotype plates to drop out of themold.

2. In a machine for casting electrotype plates utilizing molten metal,the combination including a pair of conveyors, means for driving theconveyors at a uniform rate of speed, said conveyors having bearingseats, a plurality of molds, each of the molds having a plurality ofapertures, means for connecting the molds to the conveyors, said meansincluding links extending parallel to the direction of movement of theconveyors, outwardly directed pins for journaling the links in thebearing seats of the conveyors, there being four links for each mold,inwardly directed pins projecting into the apertures in the molds, therebeing considerable clearance between the pins and the bearing seats inthe conveyors and the pins seated in the apertures in the molds so as toprevent bind ing, and cam means for deflecting the path of the moldsfrom a level even with the conveyor to another level below the conveyorwithout deflecting the conveyors.

3. In a machine for casting electrotype plates according to claim 2,wherein a vat for molten metal is located below the conveyor so that asthe molds are deflected by the cam means the molds advance into the vat,rollers engaging the end margins of the molds for guiding the molds in ahorizontal position through the vat, and means for withdrawing the moldsat a predetermined angle from the vat so as to pour off the surplusmetal from each mold, said last mentioned means guiding the molds into ahorizontal position.

4. In a machine for casting electrotype plates accord ing to claim 2,wherein dual-functional heating elements are used for heating the moltenmetal and for heating the molds to a temperature substantially equal tothe temperature of the molten metal preparatory to the castingoperation.

5. A machine for use in the manufacture of electrotype plates having ashell, the combination including a continuous length conveyor advancingin one direction in a horizontal plane, a plurality of molds, means formounting the molds on the conveyor, guide rails for supporting the moldsin a horizontal position, a vat for molten metal located under theconveyor advancing in said direction, means for tilting the moldsdownwardly into the molten metal and guiding the molds through the vatof molten metal, means including a rail for raising the molds at aninclined angle from the molten metal, said rail being adjustable so asto alter the angle of inclination of the mold so that as the mold isremoved from the molten metal the quantity of metal remaining in themold equals the volume of the backing metal desired for the electrotypeplate when cast, means including a member engaging the tail foradjusting the angle of the mold, and means for advancing the conveyorand the molds with the molten metal therein horizontally while the metalis being cooled so as to cause the metal to solidify.

6. A machine according to claim 5, wherein heating means preheat themolds before advancing into the vat of molten metal.

7. A machine according to claim 5, wherein the conveyor returns on alower level so that as the conveyor advances to the lower level, themolds are tipped to thereby eject the cast electrotype plates.

8. A machine according to claim 5 wherein a holddown is used in holdingthe shell in the bottom of the mold while advancing the mold throughsaid vat.

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